JP2008081367A - Method and apparatus for manufacturing single crystal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for manufacturing a single crystal which have excellent controllability of a single crystal composition, and can be easily maintained, and by which a single crystal having a high quality can be produced at a low cost and efficiently by a simple apparatus construction, in pulling of a single crystal of an oxide such as LiNbO<SB>3</SB>, Y<SB>3</SB>Al<SB>5</SB>O<SB>12</SB>, Lu<SB>2</SB>SiO<SB>5</SB>, Gd<SB>2</SB>SiO<SB>5</SB>, YVO<SB>4</SB>or the like and of a semiconductor such as Si, GaAs or the like. <P>SOLUTION: The method comprises using a doubly-structured crucible that is comprised of an inner crucible 1 having holes 1a formed in the side wall and an outer crucible 2, charging raw material melts 4, 5 that have different compositions into the inner crucible 1 and the outer crucible 2, respectively, separating the raw material melt 4 in the inner crucible 1 and the raw material melt 5 in the outer crucible 2 by maintaining the holes 1a at a position higher than the liquid level of the raw material melt 5 in the outer crucible 2, and after the pulling of a single crystal 6 has been started performing the control of the composition of the raw material melt 4 in the inner crucible 1 by flowing the raw material melt 5 in the outer crucible 2 into the inner crucible 1 by lowering the holes 1a to a position lower than the liquid level of raw material melt 5 in the outer crucible 2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

In the single crystal pulling method according to the Czochralski method (CZ method), the present invention provides LiNbO ₃ , Y ₃ Al ₅ O ₁₂ , Lu ₂ SiO ₅ , Gd ₂ SiO ₅ , YVO ₄ (hereinafter referred to as LN, YAG, LSO, respectively). , GSO, YVO, etc.) and a single crystal manufacturing method and manufacturing apparatus by a double crucible method suitable for growing various single crystals such as semiconductors such as Si and GaAs.

  In the growth of a silicon single crystal in a normal CZ method using a single crucible, the raw material melt in the crucible decreases as the single crystal grows, and the dopant concentration in the single crystal increases accordingly. That is, the properties of the silicon single crystal vary in the growth direction. The larger the crystal, the larger the dopant segregation in the growth direction, and the lower the effective single crystallization rate.

LSO: Ce single crystal is an excellent scintillator material. However, since the Ce ion distribution coefficient between the growing single crystal and the raw material melt is as small as 0.2, the single crystal pulled by the CZ method is used. The Ce concentration of the crystal is low in the initial stage, increases with the progress of pulling, and has a large variation within the same single crystal.
Moreover, since the melting point of the LSO: Ce single crystal is very high at 2150 ° C., it has been difficult to improve the above-described non-uniformity of Ce concentration in the CZ method using a single crucible.

Also, for LN single crystals, in order to obtain a single crystal with high composition homogeneity, Li ₂ O / (Nb ₂ O ₅ + Li, which is a congruent melting (congruent) composition in which the crystal and the melt are in equilibrium and coexist in the same composition. _Although attempts have been made to pull it up from the melt having a mole fraction of ₂ O) of 0.485 by the CZ method, it has been difficult to obtain a single crystal with high compositional homogeneity.

For this reason, for the purpose of controlling the impurity composition and the main component composition as described above, for example, a single crystal pulling using a double crucible as described in Patent Document 1 or the like, a so-called double crucible method, Conventionally used.
An example of a general single crystal manufacturing apparatus for the conventional double crucible method is shown in FIG. The double crucible shown in FIG. 6 has an inner crucible filled with a raw material melt 14 in which a single crystal 16 is pulled up by providing a cylindrical partition member 11 having a hole 11a formed in a side surface in a crucible 12. And an outer crucible part for melting the raw material.
In this double crucible, the same amount of raw material powder 15 as the raw material melt consumed by the growth of the single crystal is continuously supplied from the external raw material supply mechanism 17 to the outer crucible part, and melted by the heater 17. The composition fluctuation of the raw material melt 14 in the inner crucible portion is suppressed.

Further, for example, Patent Document 2 discloses a double crucible method in which a raw material is not supplied as a powder, but in a molten state in advance, and a single crystal is pulled.
FIG. 7 shows an apparatus for producing a single crystal by such a double crucible method. The double crucible shown in FIG. 7 has a configuration in which an inner crucible and an outer crucible are separated, and an inner crucible 21 provided with a communication pipe 21 a communicating from the bottom to the outside is disposed in an outer crucible 22. is there.
In this double crucible, the raw material melt 24 in the inner crucible 21 that decreases as the single crystal 23 grows is replenished with the raw material melt 25 in the outer crucible 22 supplied through the flow pipe 21a. At this time, the flow of the raw material melt into the inner crucible 21 is controlled by adjusting the opening in the outer crucible 22 of the distribution pipe 21 a and the liquid surface height of the raw material melt 25 in the outer crucible 22. The raw material melt composition is adjusted.
U.S. Pat. No. 2,892,739 Japanese Patent Laid-Open No. 5-148077

However, since the double crucible described in Patent Document 1 supplies the raw material as powder, it is necessary to provide a raw material supply mechanism, a stirring means for uniformly melting the raw material powder, and the like. The apparatus structure is complicated, and there are problems such as increased costs and difficulty in operation.
In addition, impurities may be mixed in from the raw material supply mechanism or the supply pipe, which may deteriorate the crystal characteristics of the single crystal.

In general, a single crystal that is difficult to pull up needs to have a slower growth rate and a smaller crystal diameter, and the amount of crystal growth per unit time is small. It must be adjusted and its feed rate slowed down.
However, the raw material powder is sufficiently melted and homogenized by the air flow caused by heating, such as flying up or not falling into the crucible, and crystals are precipitated at the dropping position. However, it also has a problem of causing non-uniform quality of the growing single crystal.

On the other hand, in the double crucible described in the above-mentioned Patent Document 2, there is no problem caused by the powder raw material as described above, but it is difficult to provide the above-mentioned flow pipe in the crucible. And had the problem of cost.
In addition, it is necessary to provide a space in which the flow pipe is disposed between the inner crucible and the outer crucible, and the unused remaining amount of the raw material melt in the outer crucible increases, resulting in high cost. It was difficult to say that it was an efficient method.
Furthermore, when replacing the raw material in the crucible, there was also a problem that it was difficult to remove the residual raw material in the distribution pipe.

  The present invention has been made to solve the above technical problem, and in the single crystal pulling of oxides such as LN, YAG, LSO, GSO and YVO, and semiconductors such as Si and GaAs, etc. by the double crucible method. An object of the present invention is to provide a manufacturing method and a manufacturing apparatus capable of efficiently obtaining a high-quality single crystal at a low cost with a simple apparatus configuration, excellent single-crystal composition control operability, and easy maintenance. Is.

The method for producing a single crystal according to the present invention uses a double crucible consisting of an inner crucible having holes formed in side surfaces and an outer crucible in pulling a single crystal by the CZ method, and the inner crucible and the outer crucible have different compositions. Each of the raw material melts is filled, the hole is held at a position higher than the liquid level of the raw material melt in the outer crucible, and the raw material melt in the inner crucible and the raw material melt in the outer crucible are separated, After starting the pulling of the single crystal, the hole is positioned lower than the surface of the raw material melt in the outer crucible, and the raw material melt in the outer crucible is caused to flow into the inner crucible.
According to such a double crucible method according to the present invention, by supplying a single crystal raw material in a melt state, the composition control of the raw material melt is facilitated, and a single crystal having a uniform composition can be stably grown. Can do.

Moreover, the single crystal manufacturing apparatus according to the present invention is a single crystal manufacturing apparatus for pulling a single crystal by the CZ method, wherein the crucible filled with the raw material melt has an inner crucible and an outer crucible with holes formed on the side surfaces. The single crucible is pulled up from the raw material melt in the inner crucible, and the raw material melt in the outer crucible is supplied and supplied into the inner crucible. To do.
As described above, the crucible is easy to process and can be used repeatedly because it is a simple crucible in which the raw material melt of the outer crucible is supplied to the inner crucible only by the holes formed in the inner crucible. In addition, the raw material filled in the outer crucible can be used without waste.

In the manufacturing apparatus, it is preferable that the inner crucible and the outer crucible are configured to be relatively movable in the single crystal pulling axis direction.
As described above, the composition of the raw material melt is controlled by the relative height position relationship between the hole formed in the side surface of the inner crucible and the liquid surface of the raw material melt in the outer crucible. A configuration that can be easily moved in the vertical direction is preferable.

Moreover, in the said manufacturing apparatus, it is preferable that the reflecting plate is installed above the inside crucible so that the raw material melt surface in the said inner crucible may be covered.
The installation of the reflector makes it easy to adjust the temperature gradient in the radial direction of the single crystal, so that the shape of the single crystal can be controlled and the quality can be improved.

As described above, the single crystal manufacturing method and manufacturing apparatus according to the present invention can supply the raw material into the crucible in a melt state with a simpler apparatus configuration than the conventional double crucible method. It has excellent operability such as control of the melt composition, is easy to maintain, and can pull up high-quality single crystals efficiently at low cost.
Therefore, according to the present invention, composition control of various single crystals such as oxides such as LN, YAG, LSO, GSO, and YVO, and semiconductors such as Si and GaAs, etc. is efficiently performed in the single crystal pulling by the CZ method. be able to.

Hereinafter, the present invention will be described in more detail with reference to the drawings.
The method and apparatus for producing a single crystal according to the present invention relates to a so-called double crucible method using a double crucible composed of an inner crucible and an outer crucible in pulling a single crystal by the CZ method.
FIG. 1 schematically shows an apparatus for producing a single crystal according to the present invention. The double crucible in the single crystal manufacturing apparatus shown in FIG. 1 is a double crucible composed of an inner crucible 1 and an outer crucible 2 having holes 1a formed on the side surfaces, and is disposed in a furnace (not shown). A heater 3 made of a high-frequency coil or the like is provided on the outer periphery of the double crucible.

Each of the inner crucible 1 and the outer crucible 2 is prepared and filled with the raw material melts 4 and 5 in advance before starting the pulling of the single crystal.
After starting the pulling of the single crystal, the composition of the raw material melt in the inner crucible 1 varies depending on the weight increase of the single crystal 6 pulled from the raw material melt 4 in the inner crucible 1. Therefore, the raw material melt 5 in the outer crucible 2 is controlled so that the raw material melt composition in the inner crucible 1 becomes constant.
The composition control of the raw material melt 4 in the inner crucible 1 is controlled by the progress of the single crystal pulling process through the hole 1a formed in the side surface of the inner crucible 1 into the inner crucible 1 and the raw material melt in the outer crucible 2. This is done by flowing 5 in.

As described above, in the double crucible according to the present invention, the raw material melt 4 in the inner crucible 1 and the raw material melt 5 in the outer crucible 2 can circulate through the hole 1 a formed in the side surface of the inner crucible 1. It is configured.
When the double crucible is used, when melting the raw material, the hole 1a is held at a position higher than the surface of the raw material melt 5 in the outer crucible 2, so that the raw material melt 4 in the inner crucible 1 and the outer crucible. The raw material melt is prepared in a state where the raw material melt 5 in 2 is separated so as not to mix.
Then, after starting the pulling of the single crystal from the raw material melt 4 of the inner crucible 1, the hole 1 a is positioned lower than the liquid surface of the raw material melt 5 in the outer crucible 2, and the inside of the outer crucible 2 is placed inside the inner crucible 1. The raw material melt 5 is introduced.

Thus, in the present invention, by supplying the single crystal raw material in the melt state, the composition control of the raw material melt can be easily performed without disturbing the single crystal as in the case of supplying in the powder state. And a single crystal having a uniform composition can be stably grown.
In addition, since the raw melt of the outer crucible is supplied to the inner crucible only by the holes formed in the inner crucible, the structure is simple, the crucible can be easily processed, and can be used repeatedly. Since the raw material filled in can be used without waste, the cost can be reduced.

  As described above, since it is necessary to adjust the height position of the hole 1a formed in the side surface of the inner crucible 1 and the liquid level of the raw material melt 5 of the outer crucible 2, in the double crucible according to the present invention, It is preferable that the inner crucible 1 and the outer crucible 2 are configured to be relatively movable in the single crystal pulling axis direction.

  The material, size, etc. of the inner crucible and the outer crucible used in the present invention are not particularly limited, and can be appropriately designed according to the type, composition, size, etc. of the single crystal to be produced.

Further, the size, position, shape, number, etc. of the holes formed in the side surface of the inner crucible are not particularly limited, and can be appropriately designed according to the type, composition, size, etc. of the single crystal to be produced. However, it is necessary to pay attention so that the raw material melt flowing from the holes causes a turbulent flow in the raw material melt in the inner crucible and does not deteriorate the quality of the single crystal.
In addition, the height position of the hole can keep the amount of raw material melt capable of pulling up the single crystal in the inner crucible, and minimize the amount of unused raw material melt remaining in the outer crucible as much as possible. It is preferred that the position be such that

  Further, in the manufacturing apparatus, as shown in FIG. 2, the surface of the raw material melt 2 in the inner crucible 1 is covered above the inner crucible 1 and is not in contact with the single crystal 6 to be pulled up. In addition, it is preferable that the reflection plate 7 is installed.

Usually, in a double crucible, since the inner crucible is immersed in the solution in the outer crucible, the temperature gradient of the raw material melt in the inner crucible is very small. For this reason, when the seed crystal is brought into contact with the raw material melt, the crystal diameter is likely to expand rapidly, it becomes difficult to control the diameter, and defects such as dislocation and inclusion are likely to occur. Furthermore, the strain is accumulated due to the rapid expansion of the diameter, and there are cases where cracks and cracks occur when the single crystal is cooled.
On the other hand, by installing the reflecting plate and returning the radiant heat from the melt to the melt again, the melt below the reflecting plate in the inner crucible becomes a higher temperature than other regions, and the melt A temperature gradient in the radial direction of the surface can be generated. Thereby, control of the single crystal diameter to be pulled up and quality can be improved.

  Further, in the double crucible according to the present invention, since the raw material solution is supplied from the outer crucible to the inner crucible with the decrease in the raw material melt of the inner crucible by pulling the single crystal, the raw material in the reflector and the inner crucible Since the positional relationship with the melt surface can be kept constant and the temperature distribution hardly changes, it is possible to obtain a uniform single crystal in the single crystal pulling direction.

EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example, this invention is not restrict | limited by the following Example.
[Example 1]
Inside the iridium outer crucible with an inner diameter of 100 mm, a depth of 100 mm, and a thickness of 2 mm, an inner diameter of iridium with an inner diameter of 80 mm, a depth of 150 mm, a thickness of 1.5 mm, and a hole with a diameter of 3 mm on the side surface at a position 30 mm from the bottom The LSO: Ce single crystal was pulled up using a double crucible having a structure as shown in FIG. 1 in which the crucible is arranged to be caught by the refractory by the flange at the upper end.
As LSO: Ce crystal raw material, 99.99% or more of Lu ₂ O ₃ , SiO ₂ , and CeO ₂ were weighed, mixed, press-molded, fired at 1400 ° C. for 10 hours, and put into the inner crucible. The raw material to be used was Ce concentration of 1.0 at% (Ce / Lu ratio), 950 g, and the raw material charged into the outer crucible was Ce concentration of 0.2 at%, 3216 g.
After melting the raw material, a seed crystal composed of an LSO: Ce single crystal was immersed in the raw material melt and pulled up at a pulling rate of 1 mm / h while rotating at 20 rpm to grow a single crystal.
The weight of the pulled single crystal was monitored by a load cell installed on the pulling shaft.
At the start of pulling, the hole on the side of the inner crucible is positioned higher than the liquid level of the raw material melt in the outer crucible, and after starting the pulling, the outer crucible is raised, and the amount of crystal weight is increased in the outer crucible. The material melt in the crucible was controlled to flow in and pulled up.
The obtained LSO: Ce single crystal had a diameter of 50 mm, a length of 150 mm, a weight of 2303 g, and a crystallization rate of 55%.

  Moreover, about the obtained single crystal, Ce density | concentration of the single crystal in each position was measured by ICP-AES, and the composition control in the raising process was evaluated. The results are shown in FIG. 3 as a graph of the relationship between the crystallization rate and Ce concentration at each time point. The crystallization rate here is the ratio of the weight of the single crystal pulled up at each time point to the total weight of the raw material melt.

Further, after the pulling of the single crystal was completed, the residual raw material melt was cooled, and the solidified residual raw material was crushed and removed for raw material replacement.
It was confirmed that both the outer crucible and the inner crucible were not repeatedly cracked or deformed, and these crucibles could be used repeatedly as they were.

[Comparative Example 1]
The LSO: Ce single crystal was pulled up using an iridium single crucible having an inner diameter of 80 mm, a depth of 80 mm, and a thickness of 2 mm.
As a LSO: Ce crystal raw material, 2216 g having a Ce concentration of 1.0 at% similar to the raw material charged into the inner crucible in Example 1 was charged into the crucible.
After melting the raw material, a seed crystal composed of an LSO: Ce single crystal was immersed in the raw material melt and pulled up at a pulling rate of 1 mm / h while rotating at 20 rpm to grow a single crystal.
The obtained LSO: Ce single crystal had a diameter of 50 mm, a length of 100 mm, a weight of 1576 g, and a crystallization rate of 71.1%.

  Moreover, about the obtained single crystal, Ce density | concentration of the single crystal in each position was measured, and the composition control in the pulling process was evaluated. The results are shown in FIG. 3 as a graph of the relationship between the crystallization rate and Ce concentration at each time point.

[Comparative Example 2]
Using a double crucible equipped with a communication pipe as shown in FIG. 7, the LSO: Ce single crystal was pulled up in the same manner as in Example 1.
In the above-mentioned pulling up, due to the presence of the communication pipe, the approach distance of the relative position between the inner crucible and the outer crucible in the pulling axis direction is more limited than in the first embodiment.
The obtained LSO: Ce single crystal had a diameter of 50 mm, a length of 90 mm, a weight of 1430 g, and a crystallization rate of 34%.

  Moreover, about the obtained single crystal, Ce density | concentration of the single crystal in each position was measured, and the composition control in the pulling process was evaluated. The results are shown in FIG. 3 as a graph of the relationship between the crystallization rate and Ce concentration at each time point.

Further, after the pulling of the single crystal was completed, the residual raw material melt was cooled, and the solidified residual raw material was crushed and removed for raw material replacement.
However, the residual raw material inside the communication pipe could not be taken out.

Comparing the pulling in Example 1 and Comparative Examples 1 and 2, as shown in the graph of FIG. 3, when the double crucible according to the present invention is used (Example 1), the conventional single crucible is It was recognized that the composition controllability was superior to that when used (Comparative Example 1).
In addition, it was confirmed that a single crystal having a uniform composition can be obtained with a high crystallization rate and a high yield even compared with the conventional double crucible method (Comparative Example 2).

[Example 2]
In the double crucible similar to that of Example 1, an iridium reflector having an inner diameter of 60 mm, an outer diameter of 78 mm, and a thickness of 1 mm is installed above the inner crucible as shown in FIG. In the same manner, single crystal pulling was performed.
By providing such a reflector, it was confirmed that immediately after the start of pulling, the rapid expansion of the single crystal diameter was suppressed and the occurrence of cracks, inclusions and cracks was also suppressed.

[Example 3]
Using the same double crucible as in Example 1, the GSO: Ce single crystal was pulled up.
Gd ₂ O ₃ , SiO ₂ , and CeO ₂ with a purity of 99.99% or more as GSO: Ce crystal raw materials were weighed, mixed, press-molded, fired at 1400 ° C. for 10 hours, and put into the inner crucible. The raw material to be used was Ce concentration of 0.75 at% (Ce / Gd ratio), 860 g, and the raw material charged into the outer crucible was Ce concentration of 0.45 at%, 2912 g.
After melting the raw material, a seed crystal composed of a GSO: Ce single crystal was immersed in the raw material melt and pulled up at a pulling speed of 1.5 mm / h while rotating at 20 rpm to grow a single crystal.
The weight of the pulled single crystal was monitored by a load cell installed on the pulling shaft.
At the start of pulling, the hole on the side of the inner crucible is positioned higher than the liquid level of the raw material melt in the outer crucible, and after starting the pulling, the outer crucible is raised, and the amount of crystal weight is increased in the outer crucible. The material melt in the crucible was controlled to flow in and pulled up.
The obtained GSO: Ce single crystal had a diameter of 50 mm, a length of 150 mm, a weight of 2085 g, and a crystallization rate of 55%.

  Moreover, about the obtained single crystal, Ce density | concentration of the single crystal in each position was measured by ICP-AES, and the composition control in the raising process was evaluated. The results are shown in FIG. 4 as a graph of the relationship between the crystallization rate and Ce concentration at each time point. The crystallization rate here is the ratio of the weight of the single crystal pulled up at each time point to the total weight of the raw material melt.

[Comparative Example 3]
Using a single crucible similar to Comparative Example 1, the GSO: Ce single crystal was pulled up.
As a GSO: Ce crystal raw material, 2006 g having the same Ce concentration of 0.75 at% as the raw material charged in the inner crucible in Example 3 was charged in the crucible.
After melting the raw material, a seed crystal composed of a GSO: Ce single crystal was immersed in the raw material melt and pulled up at a pulling speed of 1.5 mm / h while rotating at 20 rpm to grow a single crystal.
The obtained GSO: Ce single crystal had a diameter of 50 mm, a length of 100 mm, a weight of 1427 g, and a crystallization rate of 71.1%.

  Moreover, about the obtained single crystal, Ce density | concentration of the single crystal in each position was measured, and the composition control in the pulling process was evaluated. The results are shown in FIG. 4 as a graph of the relationship between the crystallization rate and Ce concentration at each time point.

[Example 4]
An iridium having an inner diameter of 50 mm, a depth of 100 mm, a thickness of 1.5 mm in an outer iridium crucible having an inner diameter of 60 mm, a depth of 60 mm, and a thickness of 1.5 mm, and a hole having a diameter of 2 mm on the side surface at a position of 20 mm from the bottom surface. The Nd: YVO ₄ single crystal was pulled up using a double crucible having a structure as shown in FIG. 1 in which the inner crucible was arranged so as to be caught by the refractory by the flange at the upper end.
Nd: YVO _{4 as} a crystal raw material, Y ₂ O ₃ , V ₂ O ₅ and Nd ₂ O ₃ having a purity of 99.99% or more are weighed, mixed, press-molded, and fired at 1400 ° C. for 10 hours. The raw material charged into the inner crucible was Nd concentration 1.75 at% (Nd / Y ratio), 153 g, and the raw material charged into the outer crucible was Nd concentration 1.0 at%, 330 g.
After melting the raw material, a seed crystal composed of an Nd: YVO ₄ single crystal was immersed in the raw material melt and pulled up at a pulling speed of 1 mm / h while rotating at 10 rpm to grow a single crystal.
The weight of the pulled single crystal was monitored by a load cell installed on the pulling shaft.
At the start of pulling, the hole on the side of the inner crucible is positioned higher than the liquid level of the raw material melt in the outer crucible, and after starting the pulling, the outer crucible is raised, and the amount of crystal weight is increased in the outer crucible. The material melt in the crucible was controlled to flow in and pulled up.
The obtained Nd: YVO ₄ single crystal had a diameter of 25 mm, a length of 90 mm, a weight of 198 g, and a crystallization rate of 41%.

  Moreover, about the obtained single crystal, Ce density | concentration of the single crystal in each position was measured by ICP-AES, and the composition control in the raising process was evaluated. The results are shown in FIG. 5 as a graph of the relationship between the crystallization rate and Ce concentration at each time point. The crystallization rate here is the ratio of the weight of the single crystal pulled up at each time point to the total weight of the raw material melt.

[Comparative Example 4]
The Nd: YVO ₄ single crystal was pulled up using a single iridium crucible having an inner diameter of 50 mm, a depth of 50 mm, and a thickness of 1.5 mm.
As a crystal raw material of Nd: YVO ₄ , 257 g having the same Nd concentration of 1.75 at% as the raw material charged in the inner crucible in Example 4 was charged in the crucible.
After melting the raw material, a seed crystal composed of a Nd: YVO ₄ single crystal was immersed in the raw material melt and pulled up at a pulling speed of 1 mm / h while rotating at 10 rpm to grow a single crystal.
The obtained Nd: YVO ₄ single crystal had a diameter of 25 mm, a length of 50 mm, a weight of 115 g, and a crystallization rate of 45%.

  Moreover, about the obtained single crystal, Ce density | concentration of the single crystal in each position was measured, and the composition control in the pulling process was evaluated. The results are shown in FIG. 5 as a graph of the relationship between the crystallization rate and Ce concentration at each time point.

As is apparent from the graphs of FIGS. 4 and 5, the present invention can be applied to pulling a GSO: Ce single crystal (Example 3 and Comparative Example 3) or an Nd: YVO ₄ single crystal (Example 4 and Comparative Example 4). When such a double crucible was used (Examples 3 and 4), it was recognized that the composition controllability was superior to that when a conventional single crucible was used (Comparative Examples 3 and 4).

It is the schematic sectional drawing which showed an example of the single crystal manufacturing apparatus which concerns on this invention. It is a schematic sectional drawing of the single crystal manufacturing apparatus of the other aspect which concerns on this invention. It is the graph which showed the relationship between the crystallization rate of the single crystal pulled up in Example 1 and Comparative Examples 1 and 2, and Ce density | concentration. 6 is a graph showing the relationship between the crystallization rate of single crystals pulled up in Example 3 and Comparative Example 3 and the Ce concentration. 6 is a graph showing the relationship between the crystallization rate of single crystals pulled up in Example 4 and Comparative Example 4 and the Nd concentration. It is the schematic sectional drawing which showed an example of the single crystal manufacturing apparatus in the conventional double crucible method. It is the schematic sectional drawing which showed another example of the single crystal manufacturing apparatus in the conventional double crucible method.

Explanation of symbols

1,21 inner crucible 1a, 11a hole 2,22 outer crucible 3,13,23 heater 4,5,14,24,25 raw material melt 6,16,26 single crystal 7 reflector 11 partition member 12 crucible 15 raw material powder 17 Raw material supply mechanism 21a Communication pipe

Claims (4)

In single crystal pulling by the Czochralski method, using a double crucible consisting of an inner crucible with holes on the side and an outer crucible,
The inner crucible and the outer crucible are filled with raw material melts having different compositions, respectively, and the holes are held at a position higher than the liquid level of the raw material melt in the outer crucible, so that the raw material melt and the outer crucible in the inner crucible are held. Separating the raw material melt from
After the single crystal pulling is started, the hole is placed at a position lower than the surface of the raw material melt in the outer crucible, and the raw material melt in the outer crucible is caused to flow into the inner crucible.   A single crystal manufacturing apparatus for pulling up a single crystal by the Czochralski method, wherein the crucible filled with the raw material melt is a double crucible composed of an inner crucible with a hole formed on a side surface and an outer crucible, An apparatus for producing a single crystal, wherein the single crystal is pulled up from the raw material melt in the crucible, and the raw material melt in the outer crucible is supplied and supplied into the inner crucible.   The single crystal manufacturing apparatus according to claim 2, wherein the inner crucible and the outer crucible are configured to be relatively movable in a single crystal pulling axis direction.   4. The single crystal manufacturing apparatus according to claim 2, wherein a reflecting plate is installed above the inner crucible so as to cover the surface of the raw material melt in the inner crucible.

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